A 16-Mb CMOS SRAM with a 2.3-μm2 single-bit-linememory cell

A novel architecture that enables fast write/read in poly-PMOS load or high-resistance polyload single-bit-line cells is developed. The architecture for write uses alternate twin word activation (ATWA) with bit-line pulsing. A dummy cell is used to obtain a reference voltage for reading. An excellent balance between a normal cell signal line and a dummy cell signal line is attained using balanced common data-line architecture. A newly developed self-bias-control (SBC) sense amplifier provides excellent stability and fast sensing performance for input voltages close to V_CC at a low power supply of 2.5 V. The single-bit-line architecture is incorporated in a 16-Mb SRAM, which was fabricated using 0.25-μm CMOS technology. The proposed single-bit-line architecture reduces the cell area to 2.3-μm² , which is two-thirds of a conventional two-bit-line cell with the same processes. The 16-Mb SRAM, a test chip for a 64-Mb SRAM, shows a 15-ns address access time and a 20-ns cycle time     

Annealing effects of a high-quality ZnTe substrate

The sharp photoluminescence (PL) and optical-reflection spectra in the bandedge region of the high-quality nondoped ZnTe substrate (100) were observed at 4.2 K. Free exciton, associated with lower and upper polaritons (EX^L and EX^U) at 2.382 eV and 2.381 eV, respectively, were clearly observed. This meant that this substrate was high quality. The intensity of a bound exciton peak (2.375 eV), which is caused by a Zn vacancy, of a neutral acceptor decreased with an increase of the Zn vapor pressures.     

Measurement and analysis of neutron-induced soft errors insub-half-micron CMOS circuits

Neutron-induced soft error rates (SERs) of subhalf-micron CMOS SRAM and Latch circuits were studied both experimentally and analytically to investigate cosmic ray neutron-induced soft errors (SEs). Because the neutron beam used in the measurement has an energy spectrum similar to that of sea-level atmospheric neutrons, our SER data corresponds to those induced by cosmic ray neutrons. The α-particle induced SERs were also measured for comparison with the neutron-induced SER's. Neutron-induced SEs occurred in both circuits. On the other hand, α-induced SEs occurred in SRAM, but not in the Latch circuits. The measured SERs agreed with simulated results. We discussed the significance of how cosmic ray neutrons affects CMOS circuits at ground level     

A novel GaAs power MESFET with low distortion characteristicsemploying semi-insulating setback layer under the gate

A low distortion GaAs power MESFET has been developed by employing a semi-insulating setback layer under the gate. The setback region was obtained by diffusing chromium from the Cr/Pt/Au gate metal in self-aligned manner. The novel power FET with the setback layer was found to be insensitive to surface trapping effects. They showed only 5-6 percent frequency dispersion of drain current at 1 MHz compared to DC condition. Because of this small frequency dispersion, the typical measurement FET, which has a surface setback layer, with a gate width of 36 mm exhibited 1.5 dB larger output power at 1 dB gain compression point than that of the FET without the setback layer. Moreover, in the π/4 shift-QPSK modulation that has been most popular in digital mobile communication system, the FET exhibited 11 dB smaller adjacent channel leakage power than the conventional one at the output power of 31.5 dBm     

Further Characterization of 394-GHz Gyrotron FU CW GII with Additional PID Control System for 600-MHz DNP-SSNMR Spectroscopy

A 394-GHz gyrotron, FU CW GII, has been designed at the University of Fukui, Japan, for dynamic nuclear polarization (DNP)-enhanced solid-state nuclear magnetic resonance (SSNMR) experiments at 600-MHz ¹H resonant frequency. After installation at the Institute for Protein Research (IPR), Osaka University, Japan, a PID feedback control system was equipped to regulate the electron gun heater current for stabilization of the electron beam current, which ultimately achieved stabilization of output power when operating in continuous wave (CW) mode. During exploration to further optimize operating conditions, a continuous tuning bandwidth of approximately 1 GHz was observed by varying the operating voltage at a fixed magnetic field. In the frequency range required for positive DNP enhancement, the output power was improved by increasing the magnetic field and the operating voltage from their initial operational settings. In addition, fine tuning of output frequency by varying the cavity cooling water temperature was demonstrated. These operating conditions and ancillary enhancements are expected to contribute to further enhancement of SSNMR signal.     

A novel ferromagnetic thermo-stent for plaque stabilization that self-regulates the temperature

The purpose of this study is to investigate the vascular wall with a thermally self-regulating, cylindrical stent made of a low Curie temperature ferromagnetic alloy. Physiologic saline was circulated in the silicone model vessel implanted with the stent. The stent-temperature remained nearly constant for variable saline flows, saline temperatures, and magnetic flux densities. Stent implants of this type in human blood vessels could potentially enable thermotherapy and temperature determination without catheterization.     

An 8-b ADC with over-Nyquist input at 300-Ms/s conversion rate

An 8-b flash analog-digital (A/D) converter (ADC) LSI for high-speed data acquisition systems such as digital oscilloscopes and wave digitizers is described. This converter can convert analog input signals over the Nyquist frequency (up to 200 MHz) at a conversion rate of 300 megasamples per second (Ms/s) without glitch errors. In addition, it can be operated at up to 440 Ms/s when input frequency is as low as 100 kHz. This ADC is fabricated by a 2.5-μm, 10-GHz f_T , Si bipolar technology called the advanced sidewall base contact structure (advanced SICOS) technology. For high-performance glitch error suppression, an inhibitory circuit and a comparator design with an inner clock buffer are developed. Both techniques require few hardware additions     

Toughening of a Particulate-Reinforced Ceramic-Matrix Composite by Thermal Residual Stress

The micromechanics involved in increased crack growth resistance, K _R, due to the addition of TiB₂ particulate in a SiC matrix was analyzed both experimentally and theoretically. The fractography evidence, in which, the advancing crack was attracted to adjacent particulates, was attributed to the tensile region surrounding a particulate. Countering this effect is the compressive thermal residual stress, which results in the toughening of the composite, in the matrix. This thermal residual stress field in a particulate-reinforced ceramic-matrix composite is induced by the mismatch in the coefficients of thermal expansion of the matrix and the particulate when the composite is cooled from the processing to room temperature. The increase in K _R of the composite over the monolithic matrix, which was measured by using a hybrid experimental-numerical analysis, was 77%, and compared well with the analytically predicted increase of 52%. The increase in K _R predicted by the crack deflection model was 14%. Dependence of K _R on the volume fraction of particulates, f _p, and of voids, f _v, is also discussed.     

High brightness and reliable AlGaInP-based light-emitting diode for POF data links

High brightness and reliability operation ring light-emitting diode (LED) is fabricated for plastic optical fiber (POF) link using the distributed Bragg reflector (DBR) mirror and antireflection (AR) coating. The ring LED exhibited optical output as high as 3.5 mW at the bias current of 100 mA. Furthermore, the projection lifetime is also estimated to be 1/spl times/10/sup 6/ h at a 35-mA data-link operating current and ambient temperature of 60/spl deg/C.     

High-performance C60 and picene thin film field-effect transistors with conducting polymer electrodes in bottom contact structure

C₆₀ and picene thin film field-effect transistors (FETs) in bottom contact structure have been fabricated with poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) electrodes for a realization of mechanical flexible organic FETs. The C₆₀ thin film FETs showed n-channel enhancement-type characteristics with the field-effect mobility μ value of 0.41 cm² V^?1 s^?1, while the picene thin film FET showed p-channel enhancement-type characteristics with the μ of 0.61 cm² V^?1 s^?1. The μ values recorded for C₆₀ and picene thin film FETs are comparable to those for C₆₀ and picene thin film FETs with Au electrodes.